Figure 12.

Comparison of two sinograms of Fly after different denoising procedures. Top to bottom: noisy sinogram Z; Münch et al. (2009 ▸) ▸; Vo et al. (2018 ▸) ▸; proposed procedure based on BM3D denoising. Although Vo et al. (2018 ▸) ▸ is very effective at removing streaks, it also considerably affects the sinogram features; note, for example, the considerably weaker bold diagonal line (indicated by the first arrow) compared with the other algorithms. Both Münch et al. (2009 ▸) ▸ and Vo et al. (2018 ▸) ▸ also distort larger areas of the sinograms, as pointed out by the second arrow; these problems are absent from the BM3D-based result. Although not visually obvious here, the differences cause severe artifacts in the tomograms, as can be seen in Figure 13 ▸.